The present invention relates to a spray device for printing machines which is used for spraying surfaces, such as a cylinder, roll, inking roll or the print material being printed, and particularly relates to control over movement of the sprayers.
A printing machine spray device according to the invention is a cleaning device for applying water, solvent or a detergent liquid onto inking rolls, printing plate cylinders, or rubber blanket cylinders of printing units of a printing machine, and particularly a web-fed offset printing machine. The invention is suitable for also applying other liquids, for instance damping water onto printing-plate cylinders, rubber blanket cylinders, damping rolls and inking rolls and, in general, is useful for uniformly distributing very small amounts of liquid over a relatively large surface, for instance on the material which is being printed in the printing unit. In the latter case, the liquid provides dosed moistening of the material being printed.
In each printing unit, two rubber blanket cylinders form a press nip through which the web or sheet material being printed is passed and that material receives the printing from the rubber blanket cylinders. Water or detergent liquid is sprayed onto the rubber blanket cylinder at the entrance side of the printing nip and is squeezed into the print material in the nip. The water or detergent liquid dissolves printing ink, residues of paper, and other dirt from the rubber blanket cylinders and transfers them to the print material being printed which then carries the undesired material away.
Instead of transmitting the dissolved dirt of the rubber blanket cylinders to the print material, a wash cloth can also be provided which is applied to the rubber blanket cylinders during the washing process and scrapes off the dissolved dirt. Printing machine cleaning devices having a wash cloth for the washing of rubber blanket cylinders are known, for instance, from EP 0 299 203 A2 and WO 89/81412.
Furthermore, the printing machine cleaning device of the present invention can be used for precisely dosed moistening of the print material after the printing and before the material travels into a dryer, or for moisturizing, prior to the printing, before the print material enters the printing unit. A spray device for spraying the printed material before it travels into a dryer is known from EP 0 299 203 A2. This is designed to avoid sudden evaporation of the volatile components of printing ink and detergent or solvent, to avoid the danger of explosion in the dryer, and to distribute the vaporization of the volatile components over the entire time of passage through the dryer.
Further prior art includes U.S. Pat. Nos. 1,042,012; 2,264,521; 3,545,381, Federal Republic of Germany Patents 12 29 547; 34 46 608 A1; DE 37 23 400 C1; DE 39 00 657 C1 and Patent Abstracts of Japan M-946, Mar. 7, 1980, Vol 14/No. 121 relating to JP 1-31/772.